New research from Finland suggests that higher blood levels of indolepropionic acid - a product of gut bacteria that is increased by a fiber-rich diet - may help to protect against type 2 diabetes.
Writing about the discovery in the journal Scientific Reports, the team - led by researchers from the University of Eastern Finland in Kuopio - suggests that it increases our understanding of the important part played by gut bacteria in the relationship between diet, metabolism, and health.
Diabetes is a disease in which the blood contains too much sugar, or glucose - a vital source of energy for the body's cells.
Levels of blood sugar are regulated by the hormone insulin, which is made in the pancreas.
The type of diabetes that develops depends on whether the high blood glucose results from lack of insulin (type 1 diabetes) or the body's inability to use insulin (type 2 diabetes).
Molecular factors in type 2 diabetes less well-understood
Once a disease occurring only in adults, the number of children with type 2 diabetes is now on the rise.
- Adults with diabetes have a two- to threefold higher risk of heart attacks and strokes.
- Type 2 diabetes patients can be treated with oral medication, but they may also need insulin.
- More than a fifth of healthcare spending in the U.S. is for people diagnosed with diabetes.
The global prevalence of diabetes among adults (90 percent of which is type 2 diabetes) has gone up from 4.7 percent in 1980 to 8.5 percent in 2014.
In the United States, there are more than 29 million people living with diabetes. There are also 86 million living with prediabetes, a serious condition that raises the risk of developing type 2 diabetes and other lifelong health problems.
In their study introduction, the researchers note that it is now well-known that factors such as genes, lifestyle, and diet can influence the risk of developing type 2 diabetes.
However, what is less clear is what happens at the molecular level to link these factors to the disease.
The new study uses metabolomics, a relatively new technology that allows scientists to quickly assess the metabolite profiles of people.
Metabolites are molecules that cells in the body - including gut bacteria - produce as byproducts of their activity.
Indolepropionic acid may protect against type 2 diabetes
Using a particular tool called "nontargeted metabolomics analysis," the researchers assessed the metabolite profiles of 200 participants in the Finnish Diabetes Prevention Study who had impaired glucose tolerance and were overweight when the study began.
The participants fell into two groups. One group developed type 2 diabetes within 5 years, and the other group did not develop type 2 diabetes during the 15 years of follow-up.
When the researchers compared the metabolite profiles of the two groups, they found that what stood out was differences in levels of indolepropionic acid and certain lipid metabolites.
Further analysis suggested that having high blood levels of indolepropionic acid, a byproduct of gut bacteria, appeared to protect against developing type 2 diabetes.
Also, a diet rich in fiber and whole grain foods appears to increase levels of indolepropionic acid, which in turn raises the amount of insulin produced by the beta cells in the pancreas, note the authors.
The team confirmed the findings by looking at the link between indolepropionic acid and risk for type 2 diabetes in the data from two other studies: the Finnish Metabolic Syndrome In Men Study, and the Swedish Västerbotten Intervention Project. These also showed that indolepropionic acid appears to protect against type 2 diabetes.
The researchers suggest that their study shows that it may be more feasible to use metabolite profiles rather than identifying the bacteria themselves (which is a more complex process) to look at links with diseases such as diabetes.
"Earlier studies, too, have linked intestinal bacteria with the risk of disease in overweight people. Our findings suggest that indolepropionic acid may be one factor that mediates the protective effect of diet and intestinal bacteria."
Corresponding author Dr. Kati Hanhineva